High velocity through-drying system



Nov 24, 1970 J. A. VILLALOBOS 3,

HIGH VELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5 Sheets-Sheet'1' I IN VENTORS Jase 0b J4. Vfla/oboS BY HTTOAWEYS 1970 J. A.VILLALOBOS 3,

HIGH VELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5 Sheets-Shet 2IN VENTOR.

Jbse bb 14 WHO/01205 BY QT TOPNEYS Nov. 24, 1970 J. A. VILLALOBOS HIGHVELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5' Sheets-Sheet :5

X WW n-r TORNE Y5- Nov. 24, 1970 J. A. VILLALOBOS 3,541,697

I HIGH VELOCITY THROUGH-DRYING SYSTEM 5 Sheets-Sheet 4 Filed Aug. 1,1968 INVENTOR. Jseph 14. lfi/M/obos BY HTTOPNEYS.

Nova 24, 1970 VILLALQBQS 3,541,697

HIGH VELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5 Sheets-Sheet 5v Comb. Chamber 60 45 4. 42 /8 E 1 I E U I L :'v 52 I .1

IN VENTOR.

JErscph A V/'//a/obo5 United States Patent 3,541,697 HIGH VELOCITYTHROUGH-DRYING SYSTEM Joseph A. Villalobos, Ramsey, N.J., assignor toAER Corporation, Ramsey, N.J., a corporation of New Jersey Filed Aug. 1,1968, Ser. No. 749,549 Int. Cl. F26b 11/02 US. Cl. 34-115 17 ClaimsABSTRACT OF THE DISCLOSURE A system for drying a wet web supported on anopenwork surface in 'which nozzles direct a plurality of jets of highvelocity hot air from a combustion chamber onto the surface of the web.A first portion of the high velocity air produces a scrubbing action atthe surface of the web and is returned to the combustion chambertogether with a quantity of water from the web. A secondary portion ofthe air passes through the web and through the openwork surface to anexhaust space. The system includes means for regulating the jets acrossthe width of the web and in the direction of travel of the web with thesurface. The jet-forming means is readily moved out of cooperativerelationship with the surface to permit access to the interior of thesystem for repair and maintenance.

BACKGROUND OF THE INVENTION Various systems are known in the prior artfor drying a Wet Web. In one particular arrangement known in the priorart, the web is supported on a honeycomb roll as it travels through thesystem. Hot air is supplied to a relatively large plenum chamberadjacent the roll. An exhaust system draws this heated air through theWeb. A certain percentage of the circulating air is continuouslydischarged. In one form of this system, the hot air is supplied to aspace over the roll, is drawn radially through the web into the interiorof the roll and is exhausted axially from the ends of the roll.Alternatively, the heated air may be supplied axially through the openends of the roll and the exhaust system may draw the air from inside theroll radially outwardly.

While systems of the type described above achieve higher drying ratesthan were possible with systems theretofore used, they embody a numberof defects. First, the amount of air which can be drawn through the webis limited by the water content of the web and thus the possible dryingrate which can be achieved is limited. Secondly, arrangements of theprior art using the system described above do not permit ready access tothe roll such as is required, for example, when the web breaks, a nottoo rare occurrence in handling webs of the type to which the system isapplied. Another drawback of systems of the type described above is thatthey do not ensure even drying of the web across its width. Stillanother defect of a system of this type is its lack of versatility. Thatis to say, while the arrangement is applicable to drying of a relativelypermeable web, it has no utility whatever in drying impermeable webs.

I have invented an improved web drying system which overcomes thedisadvantages of web drying systems of the prior art. My system achievesmarkedly greater drying rates than are possible by use of systems of theprior art. My improved system ensures even drying of the web across itswidth. Apparatus incorporating my system is arranged to permit readyaccess to the web supporting element in the event of web breakage or thelike. My apparatus, while it is especially adapted for drying perviouswebs, may be employed as well to dry imprevious webs.

One object of my invention is to provide an improved web drying systemwhich is a high velocity throughdrying system.

Another object of my invention is to provide an improved web dryingsystem for achieving drying rates heretofore unobtainable.

A further object of my invention is to provide an improved web dryingsystem which permits ready access to the surface supporting the web.

A still further object of my invention is to provide an improved webdrying apparatus 'which ensures even drying across the surface of theWeb.

Yet another object of my invention is to provide an improved web dryingapparatus which is more versatile than are drying systems of the priorart.

Other and further objects of my invention will appear from the followingdescription.

In general my invention contemplates the provision of an improved webdrying system in which jets of high velocity hot air from a combustionchamber are directed onto the surface of the wet web which is supportedon an openwork roll or belt. A first portion of the high velocity airproduces a scrubbing action at the surface of the web and, together witha relatively large quantity of water, is drawn away from the web surfaceand returned to the combustion chamber. A secondary portion of thejetted air passes through the web and through the open work surface toan exhaust space. The apparatus incorporating my system includes twohood sections which can readily be moved out of cooperative relationshipwith the web supporting surface to permit access thereto. Preferably, Iprovide means for regulating the jets of air both in a directiontransversely of the web and in the direction of travel thereof.

BRIEF DESCRIPTION OF THE DRAWINGS :In the accompanying drawings whichform part of the instant specification and which are to be read inconjunction therewith and in which like reference numerals are used toindicate like parts in the various views:

FIG. 1 is a perspective view of one embodiment of my improved web dryingsystem.

FIG. 2 is an end elevation of the form of my system shown in FIG. 1 withparts removed.

FIG. 3 is a side elevation of the form of my improved web dryingapparatus illustrated in FIGS. 1 and 2 with a part broken away.

FIG. 4 is a fragmentary end elevation of a portion of the system shownin FIGS. 1 to 3 with a part broken away.

FIG. 5 is a fragmentary plan view illustrating a detail of the form ofmy improved air drying system shown in FIGS. 1 to 4.

FIG. 6 is a schematic view illustrating an alternate embodiment of myimproved web drying system.

FIG. 7 is a sectional view of my improved web drying apparatusillustrating an alternate air distribution system.

FIG. 8 is a diagrammatic view illustrating the flow of drying air in myimproved Web drying system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,my improved drying system includes a roll or drum, indicated generallyby the reference character 10, around which the web 12 to be dried istrained by idler rollers 14 and 16 supported in any suitable mannerknown to the art. The roll or drum 10 includes a cylindrical openworkbody 18 so formed as to provide a multiplicity of openings 20 leading tothe interior of the body 18. Preferably the body Patented Nov. 24, 197018 is so constructed that from 85% to 90% of its surface is made up bythe openings 20. Respective end plates 22 and 24 close the ends of thedrum 10. A shaft 26 supports the drum for rotary movement in bearings 28and 30 carried by uprights 32 and 34 supported on beams 36 and 38 whichmay make up part of a floor structure of a mill or the like.

For reasons to be explained more fully hereinafter, I connect respectiveexhaust conduits 40 and 42 through the end plates 22 and 24 of drum orroll 10 to the interior of the drum 10. These connections may be madethrough the end plates 20 and 22 with suitable seals 44 being providedto prevent the escape of air while permitting relative rotation betweenthe end plates and the conduits 40 and 42. It will be appreciated thatshaft 26 extends through each of the conduits 40 and 42 to the bearings28 and 30.

My drying apparatus further includes respective hood sections, indicatedgenerally by the reference characters 46 and 48, each of which has anenclosure comprising a top 50, an end 52, and respective sides 54 and56. A frame 58 carried by legs 60 on the beams 36 and 38 supports thehood sections 46 and 48. I secure respective pairs of roller supports 62and 64 to the sides 54 and 56 of each of the sections 46 and 48. Thesupports 62 and 64 carry respective rollers 66 and 68 which ride on camtracks 70 and 72 on the frame 58. Piston and cylinder assemblies 74pivotally supported on a bracket 76 on the frame have rods 78 connectedto the respective roller supports 64 on the sides of frame 58. Thearrangement is such that when access to the roll 10 is desired, fluidunder pressure from any suitable source (not shown) may be supplied tothe assemblies 74 to cause them to draw the respective sections 46 and48 radially outwardly away from the roll 10. The shape of the cam tracks70 and 72 is such that in the course of this movement of the sectionsaway from the drum 10, the sections pivot slightly around the rollers 66so as to permit access to the drum.

Each of the sections 46 and 48 includes an air supply duct 80 extendinginto the interior of the section through the wall 54. A return duct 82extends through wall 54 into the space within each of the hood sections46 and 48.

I connect each of the supply ducts 80 to a distributing header 84extending across the width of the section 46. Respective distributorconnections 86 carry air from the header 84 to respective lead-inconnections 88 which direct air through openings 90 in one arcuate wall92 of each of a number of inner high pressure air chambers 94distributed across the sections 46 and 48. The other wall 96 of each ofthe chambers 94 is provided with a plurality of pairs of generallyradially inwardly directed flanges 98 and 100 extending transversely ofthe drum 10 to form a plurality of elongated transversely extendingnozzles, spaced circumferentially of the roll 10 for directing jets ofhigh velocity air onto the surface of the web 12 supported by theopenwork frame 18. Each of the distributing conduits 88 supplies one ofa number of chambers 94 of the hood section arranged transversely acrossthe roll 10. Dividers or partitions 102 extending between walls 92 and96 are spaced across the hood to separate the chambers 94.

Adjacent each of the connecting ducts 86 I provide a respective damper104 having a shaft 106 which extends outwardly to a handle 108 outsidethe hood to permit the supply of air provided by that particulardistributor duct to be varied. In this Way I am able to regulate the airsupplied to the web 12 over a plurality of narrow sections across itswidth so as to ensure that drying occurs evenly across the width of theweb.

The transversely elongated jets of high velocity air emanating from thenozzles formed by flanges 98 and 100 are directed onto the surface ofthe web 12 so as to provide a scrubbing action thereat. As has beenexplained hereinabove, the amount of air which can pass through the webis limited by the amount of water contained therein.

I provide means for returning a portion of the high velocity aircarrying moisture which has been removed from the web 12 by thescrubbing action referred to hereinabove. A plurality of short lengthsof tubing or ports 110 extend through wall 96 at locations between thenozzles, through the chambers 94 and through the wall 92 of chambers 94to the space within the hood section outside the high pressure airchambers 94. As has been explained hereinabove, return ducts 82 leadinto this space to permit the return air to be carried out of each hoodsection. It will readily be appreciated of course that there are noreturn tubes 110 in the region wherein high velocity air is introducedby one of the distributor ducts 88.

As has been explained hereinabove, a portion of the high velocity airimpinging on the surface of the web 12 is returned through the tubes 110and through the duct 82. Another portion of this supply air travelsthrough the web 12 and through the openings in the open frame 18 to thespace within the roll 10 carrying moisture therewith. This moistureladen air is exhausted through the exhaust conduits 40 and 42 connectedto the ends of the roll.

Referring now to FIG. 8, I have shown a diagrammatic view of the airsystem of my web drying arrangement. Any suitable means, such as ablower 112, supplies air from a combustion chamber 114 to the two inletducts 80 associated with the respective hood sections 46 and 48. Thisair produces high velocity jets through nozzles formed by flanges 98 and100. A portion of this high velocity air impinging on the surface of theweb 12 removes moisture from the web by a scrubbing action and returnsthrough conduits 110 to the spaces within the hood sections outside thehigh pressure air chambers 94 and travels outwardly through the returnducts 82. This air is returned to the combustion chamber 114 asindicated schematically by the broken line 116 in FIG. 8. The otherportion of the air from the jets formed by flanges 98 and 100 travelsthrough the web and through the openings 20 in framework 18 to the spacewithin the openwork roll 10. This air is exhausted through the ducts 40and 42 by any suitable means such, for example, as by an exhaust blower118.

In the structure just described, I have provided an arrangement whereineach of the hood sections 46 and 48 is divided into a plurality ofsub-sections or chambers 94 transversely of the web so as to facilitateeven drying across the web. In many instances it is desirable that thehood be divided additionally in the direction of travel of the web sothat further control of moisture removal is possible. Referring to FIG.7, I have shown such an arrangement in which, in addition to thepartitions 102 which form the transverse sub-section, I provide anotherpartition 120 extending transversely of the hood so as to divide thehood section into sub-sections in the direction of travel of the web. Insuch an arrangement I provide an auxiliary high velocity air supply duct122 leading to a header 124 from which connecting ducts 126 direct airto distributing ducts 128 connected to openings in the wall 92 on theother side of the partition 120 from the openings 90. Baflles 130associated respectively with the connecting ducts 128 are provided withhandles 132 for regulating the flow of air from the distributing headerand through the connecting duct 128 to the particular section with whichthat duct is associated. It will readily be appreciated that byadjusting all of the baflies 104 and 130 any desired degree of controlof drying of the web both in the direction of travel thereof and acrossthe surface thereof can be achieved. For the purpose of controllingdrying of the web in the direction of travel thereof it may not benecessary to provide the additional partition or partitions 120. Thatis, it may be suflicient merely to provide one or more auxiliarydistributing headers 124 spaced in the direction of travel of the webwith respect to header 84.

I provide each of the hood sections 46 and 48 with an air seal 134extending entirely around the periphery of the hood adjacent the roll topermit the area of the web covered by the hood to be pressurized tocause some of the air to be forced through the web. I have found this tobe required to produce the optimum drying rates even though a negativepressure exists within the drum. Seals 134 may be of any suitableconstruction which will prevent the hot high velocity air from spillingout around the edge of the hood section. I have found that a flexiblewire brush-like seal which presents a large pressure drop to the airflow while at the same time having sufiicient flexibility to accommodateexpected variations in drum circumference is suitable for this purpose.Each of the hoods further includes a closure plate 136 extending fromadjacent the upper portion of the roll 10 at the center thereof to thetop wall 50 of the corresponding hood.

Referring now to FIG. 6, I have shoWn an alternate embodiment of myimproved web drying system in which an openwork endless conveyor or belt138 carried by rolls 140 and 142 is adapted to support a web 144 to bedried for movement in the direction if the air indicated in the figure.I arrange a hood, indicated generally by the reference character 146,over the web 144 on the upper portion of the belt 138 between rolls 140and 142. Hood 146 includes a first chamber 148 to which I supply highvelocity air by means of a duct 150. Chamber 148 includes an upper wallor partition 152 and a lower wall 154. I form wall 154 with a pluralityof pairs of downwardly extending flanges 156 and 158 directed towardeach other so as to form nozzles extending transversely of the web 144It will readily be appreciated that the hood 146 can be divided intosections across the web 144 as well as sections along the length of theweb in a manner analogous to that in which sections are formed in theembodiment of my invention described hereinabove.

A plurality of return conduits 159 extend through portions of the lowerchamber wall 154 between flanges 156 and 158 and through the upper wall150 to a space 160 within the hood above chamber 148. I connect a returnduct 162 to the space 160 so as to return air to the combustion chamber.I provide a seal 164 around the periphery of hood 146 at the bottomthereof so as to prevent the escape of hot high velocity air from underthe hood.

An exhaust chamber 166 below the upper portion of conveyor 138 registerswith the hood 146. A portion of the high velocity air supplied by thenozzles formed by flanges 156 and 158 passes through the web 144 andthrough the openwork conveyor 138 to chamber 166. An exhaust conduit 168carries the air from chamber 166 to the exhaust.

In operation of my improved high velocity throughair drying system, airunder pressure is supplied to both ducts 80 from the combustion chamber114. The amount of this air passing to each of the sections of the hoodscan be regulated by adjusting dampers 104- to ensure even drying acrossthe web 12. If desired, the machine may be divided into sections in thedirection of travel of the Web and baffles 130 can be adjusted tocontrol the relative drying effect of the two sections in the directionof travel of the Web.

Air supplied by the ducts 80 travels through the header 84 down throughthe connecting ducts 86, past the dampers 104 and through distributingducts 88 to the high pressure air space 94 This air emerges from thenozzles formed by flanges 98 and 100' in the form of transverselyelongated jets of high velocity air. By way of example, the air emergingfrom the nozzles formed by the pairs of flanges may have a velocity ofthe order of about 20,000 f.p.m. It may be at a temperature of about 600F. In order for maximum drying with a minimum horsepower expenditure tobe achieved, it is desirable that the nozzels be very close to the web.The web itself may be travelling at a speed of between 3,000 to 4,000f.p.m.

The high velocity hot air impinging on the surface of the web 12produces a scrubbing action thereat so that a relatively large quantityof moisture is picked up by this air. A portion of the high velocity aircarrying moisture travels backwardly through the return ducts to thespace within the hood outside the chamber 94 from whence it is returnedto the combustion chamber through the return duct 82. Another portion ofthe air supplied by the nozzles travels through the web and into thespace inside the roll 10. It will be understood that as the air travelsthrough the web, it picks up additional moisture. This through air iscarried to the exhaust through the conduits 40 and 42.

I have discovered that a suitable inter-nozzle spacing for use in mysystem is about 3 /2 inches between centers. Under the conditionsdescribed above, I have been able to achieve a drying rate of between 30to 35 lbs. of water per square foot per hour as contrasted with a dryingrate of about 20 lbs. of water per square foot per hour by systems ofthe prior art described above.

As has been pointed out hereinabove, web speed in a system to which Imay apply my dryer is from 3,000 to 4,000 f.p.m. In the event that thereis a web break, very large quantities of paper accumulate before theapparatus can be stopped. With the relatively high temperature of theair being supplied, it is essential that the system be able to be openedup rapidly so as to permit the web carrier to be cleared in order toavoid the danger of fire. In my system, if such a break occurs, theapparatus is stopped and fluid under pressure is at once applied to thecylinders 74 to cause them to move the hood sections 46 and 48 outwardlyof the roll 10' and to tilt them slightly in the course of so doing topermit ready access to the cylinders.

It will be seen that I have accomplished the objects of my invention. Ihave provided an improved web drying system for achieving much higherdrying rates than are possible by use of systems of the prior art. Mysystem is so arranged as to ensure even drying of the web. It permitsready access to the inside of the hood in the event of a Web break orthe like.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of myclaims. It is further obvious that various changes may be made indetails within the scope of my claims without departing from the spiritof my invention. It is, therefore, to be understood that my invention isnot to be limited to the specific details shown and described.

Having thus described my invention, What I claim is:

1. A system for drying a web including in combination, means providing aforaminous surface for supporting said web with an outer surface of theweb remote from said foraminous surface, means for directing a pluralityof jets of high velocity drying gas onto said outer surface of thesupported web, means for removing a portion of said gas in a directionoutwardly from said outer surface after impingement thereon whilepermitting a portion of the gas to pass through said web and throughsaid foraminous surface and means for removing another portion of thegas which has passed through said surface.

2. A system as in claim 1 in which said jet directing means is elongatedtransversely of said supporting surface.

3. A system as in claim 1 in which said jets are positioned across saidsurface.

4. A system as in claim 1 in which said jets are elongated and extendtransversely of the surface.

5. A system as in claim 1 in which said jets extend transversely of saidsurface and means for regulating the amount of air supplied totherespective jets.

6. A system as in claim 1 in which said jets are positioned along saidsurface and means for individually regulating the air supplied to therespective jets.

7. A system for drying a web including in combination, means providing aforaminous surface for supporting said web with an outer surface of theweb remote from said foraminous surface, a hood provided with a pressurechamber formed in part by a first wall conforming generally to the shapeof a portion of said foraminous surface and by a second wall spaced fromsaid first wall, means forming a plurality of nozzles in said firstwall, means for supplying gas under pressure to said chamber to producea plurality of high velocity jets of gas from said nozzles directedtoward said outer surface of said web on said foraminous surface, meansfor removing a first portion of said gas outwardly from said outersurface after impingement thereon and for returning said first portionof the gas to said supplying means and means for removing anotherportion of said gas which has passed through said surface.

8. A system as in claim 7 in which said surface providing means is adrum.

9. A system as in claim 7 in which said surface providing means is ahorizontally disposed conveyor.

10. A system as in claim 7 including means providing a seal between thefirst wall and said surface providing means, said seal extending aroundsaid first wall.

11. A system as in claim 7 including a flexible wire brush seal betweensaid first wall and said surface providing means, said seal extendingaround the periphery of said first wall.

12. A system as in claim 7 in which said means for returning said firstportion of said high velocity air comprises a duct extending throughsaid first and second Walls between said nozzles.

13. A system as in claim 7 including means mounting said hood formovement with relation to said surface providing means and actuatablemeans for moving said hood away from said surface providing means 14. Asystem as in claim 7 including means for regulating the supply of gas tosaid nozzles in a direction transversely of said surface-providingmeans.

15. A system as in claim 7 including means for moving said surfaceproviding means and means for regulating the supply of gas to respectivenozzles in the direction of movement of said surface-providing means.

16. A system as in claim 7 including means for moving said surfaceproviding means, means for regulating the supply of gas in a directiontransverse to said direction of movement and means for regulating thesupply of gas in said direction of movement.

1'7. A system for drying a Wet web including in combination, a drumhaving a generally cylindrical foraminous wall and having a pair of endplates, a first hood section provided with a pressure chamber formed inpart by a first wall conforming generally to the shape of a portion ofsaid surface and by a second wall spared from the first wall, meansforming a plurality of nozzles in said first wall, a second hood sectionhaving a pressure chamber formed in part by a first wall conforminggenerally to the shape of another portion of said surface and by asecond wall spared from the first wall, means forming a plurality ofnozzles in the second section first wall, means mounting the respectivehood sections for movement between operative positions at which thefirst walls are adjacent to said surface and inoperative positions atwhich the first walls are remote from said surface, means at theperipheries of said first walls forming air seals between the sectionsand the surface in the operative positions of the sections, means forsupplying gas under under pressure to said chambers to produce aplurality of high velocity of jets of gas from said nozzles directedtoward said web or said surface, means for returning a portion of thegas directed against said web to said supplying means, and means forremoving another portion of said gas through said web.

References Cited UNITED STATES PATENTS 1,533,086 4/1925 Baker 34-131 X3,222,279 12/1965 Taylor 34122 3,284,920 11/1966 Hayrinen et al. 341223,406,466 10/1968 Smith 34-155 3,435,751 4/1969 Goodman et a1. 34155 X3,447,247 6/1969 Daane 34-155 X ROBERT A. OLEARY, Primary Examiner T. W.STREULE, Assistant Examiner US. Cl. X.R. 34-122, 155

253 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION P.tent N 3Datd NoVeInber 24,

Inventor) Joseph A. Villalobos It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 7, line 35:

A period should be inserted after 'means" Column 8, line 9:

" spared" should be spaced Column 8, line 14:

" spared" should be spaced Column 8, line 23:

"under" (second occurrence) should be deleted.

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